Sub Hide_Rows()
Dim LastRow As Long
Dim rng As Range
Application.ScreenUpdating = False
LastRow = Cells(Rows.Count, 1).End(xlUp).Row
For Each rng In Range(Cells(4, 1), Cells(LastRow, 1))
If rng.Font.Bold = True Then rng.EntireRow.Hidden = True
Next rng
Application.ScreenUpdating = True
End Sub